Hothouse Earth: An Inhabitant’s Guide

Book Preface

This book was written mostly over a six-month period, during the course of which the COP26 (the 26th Conference of Parties) UN Climate Change Conference was staged in Glasgow. Putting it together has been quite a challenge, not only because there is such a vast amount of material out there, but also because both the science and the policy are constantly changing. In retrospect, having to squeeze a quart into a pint pot has actually worked in my favour, and hopefully yours too, by helping to concentrate the mind and forcing me to zero in on the core issues at the heart of the climate emergency. The end product is a small book with a big message.
It is fortuitous that the final pulling together of material coincided with the COP26 summit, providing – as it did – a more credible idea of where we are likely headed. It was billed by many, including me, as arguably the most important meeting in the history of humankind, and I attended with grateful humility and with this always in mind. Hopes were high that the outcome of the two weeks of discussion, debate and negotiation might be a glimpse of a realistic pathway out of the dark place we find ourselves in; an attainable route towards the goal of keeping the global average temperature rise (since pre-industrial times) this side of the 1.5°C (2.7°F) so-called dangerous climate change guardrail. Unfortunately, this was not to be.
True, there were plenty of fine promises, on everything from protecting forests to reducing methane emissions, cutting out coal and throwing cash at the majority, or developing, world to help fund carbon-reducing measures, but on the detailed mechanisms, legal frameworks and monitoring required to ensure fulfilment of these pledges there was next to nothing.
Some early post-COP26 modelling averred that, if pledges were all met and targets achieved, then we might be on track for ‘just’ a 1.9°C (3.4°F), or even 1.8°C (3.2°F), global average temperature rise. Firstly, however, this is a very big if indeed. Secondly, such predictions fly in the face of peer-reviewed research published pre-COP26, which argues that a rise of more than 2°C (3.6°F) is already ‘baked-in’ or, in plain language, certain.
The post-COP26 reality is this. To have even the tiniest chance of keeping the global average temperature rise below 1.5°C, we need to see emissions down 45 per cent by 2030. In theory, this might be possible, but in the real world – barring some unforeseen miracle – it isn’t going to happen. Instead, we are on course for close to a 14 per cent rise by this date that will almost certainly see us shatter the 1.5°C guardrail in less than a decade.
This book takes as its starting premise, then, the notion that, practically, there is now no chance of dodging a grim future of perilous, all-pervasive, climate breakdown. It is no longer a matter of what we can do to avoid it, but of what we should expect in the decades to come, how we can adapt to a hothouse world with more extreme weather and what we can do to stop a bleak situation deteriorating even further.
I ought to make clear here that the terms ‘hothouse Earth’ or ‘greenhouse Earth’ are used formally, in a definitive sense, to describe the state of our planet in the geological past when global temperatures have been so high that the poles have been ice-free. A hothouse state, however, is not required for hothouse conditions, which are already becoming far more commonplace, and fast becoming the trademark of our broken climate. What I mean by hothouse Earth, then, is not an ice-free planet, but a world in which lethal heatwaves and temperatures in excess of 50°C (122°F) in the tropics are nothing to write home about; a world where winters at temperate latitudes have dwindled to almost nothing and baking summers are the norm; a world where the oceans have heated beyond the point of no return and the mercury climbing to 30°C+ (86°F+) within the Arctic Circle is no big deal.
To all intents and purposes, this is the hothouse planet we are committed to living on; one that would be utterly alien to our grandparents. The fact is that a temperature rise of 2°C – which is likely the minimum we are committed to – may not sound like much, but remember that this is an average temperature. In some parts of the planet, the increase will be far higher. In addition, even this small rise will drive extreme high temperature events beyond anything experienced in human history. A child born in 2020 will face a far more hostile world than its grandparents. Compared with someone lucky enough to be born in 1960, one study estimates that – on average – they will experience seven times more heatwaves, twice as many droughts and three times as many floods and harvest failures. The reality could very well be far worse, and it will be for the billions of vulnerable people living in the majority world. Looking at the broader picture, anyone younger than 40 today will suffer ever more frequent bouts of extreme weather that would be virtually impossible in the absence of global heating.
In the pages that follow, I have tried – using the most recent observations and latest peer-reviewed research – to shine a light on how our familiar world is already changing, and how it will be completely reshaped in the decades ahead. I have sought to do this by focusing on three facets of the climate emergency. First, to place the changes to our climate caused by human action in context, by taking a trip through our planet’s 4.6-billion-year history, during which time conditions ranged from icehouse to hothouse and back again on many occasions. Second, to zero in on the current global heating episode and drill down into the evidence for the accelerating breakdown of our once stable climate. Third, to dissect the wide-ranging consequences of contemporary heating in more detail, from storm, flood, fire and drought to mass migration, water wars and health issues, along with hard-to-predict ‘stings in the tail’, such as Gulf Stream collapse and methane ‘bombs’. A concluding section looks ahead to possible futures, addresses what we need to do now to minimise the impact of dangerous climate breakdown and considers whether technology can save us. It also rams home the message that – even at this late stage – it remains vital that we cut emissions to the bone as soon as we possibly can.
As a trained geologist, I have always tended to set more store by observation and measurement than modelling or simulation, although both certainly have their place, particularly in trying to pin down future climate scenarios. Consequently, the content of this book is driven as much by current observation of climate trends and knowledge of past episodes of climate change as it is by model-based forecasts of what we might expect in the decades and centuries to come.
This is important because there is little doubt that our climate is changing for the worse far quicker than predicted by earlier models. It is also the case, research has revealed, that climate scientists – as a tribe –tend to gravitate towards a consensus viewpoint rather than go out on a limb, and they are inclined to make forecasts that underplay the reality. This does not help us minimise the impacts of the dangerous climate breakdown that we now know is on our doorstep. Far from it. In order to be as prepared as we can be, we need to plan for the worst even as we hope for the best.
A note on terminology. ‘Global warming’ has a cosy feel to it that is far from justified by the reality, while the rapidly increasing incidences of extreme weather show that our once stable climate is not simply changing, but well on its way to failing. To reflect this, I will be mostly using the alternative terms ‘global heating’ and ‘climate breakdown’. Both are coming into general usage because they far more accurately describe what is happening to our world and our climate.